i work at a camp that has a Hobart Mig welder which nobody uses because it's not feeding wire. Gas is fine.
it makes me sad to see it waste away and grow dust and cob webs.
any ideas on where to start?
Release the drive roller tension and see if the motor spins the rollers, without the wire feeding,see if the motor speed changes with the wire feed knob position.
If the motor doesn't spin, try unhooking the motor and running it from 12v power.
If the motor spins, try feeding some wire through the wire feed conduit by hand, it should take almost no effort to push wire to the torch tip.
Robert